Outgoing U.S. President Barack Obama commuted Lopez' sentence, which will expire on May 17, according to a list of commutations announced by the White House.

Celebrations started almost immediately, while Clarissa Lopez, daughter of Lopez, will hold a press conference Wednesday at 10 a.m. in reaction to his release at the Roberto Clemente Coliseum in San Juan, Puerto Rico.

Lopez was born in Puerto Rico in 1943 and upon returning to Chicago after serving in the Vietnam War, he joined the struggle for Puerto Rican rights and participated in acts of civil disobedience and other actions.

In 1976, he joined the clandestine fight for the independence of Puerto Rico as a member of the Armed Forces of National Liberation. In 1981, he was captured by the FBI and accused of "conspiracy" for his militancy in the FALN.

At the time of his capture, he proclaimed himself a prisoner of war, protected in the first protocol of the Geneva Convention of 1949. The protocol protects Lopez from prosecution for having been arrested in a conflict against colonial occupation.

The U.S. did not recognize Lopez' demand and sentenced him to 55 years in prison and after an alleged attempt to escape, the sentence was increased to 70 years in prison, 12 of which he spent in solitary confinement.

Former U.S. President Bill Clinton in 1999 offered him a pardon, along with 13 FALN members who accepted, but Lopez rejected it because it included completing 10 more years in jail. Leaders from around the world, as well as human rights organizations, have demanded Lopez' release for many years.

On June 18, 2012, the U.N. Decolonization Committee approved a resolution, promoted by Cuba, which called for the recognition of Puerto Rico's right to independence and self-determination and urged the release of all pro-independence prisoners in the United States.